Planar light source devices are known in the prior arts such as Japan Patent Laid Open Nos. 21883/2001, 00017/1990 and 84618/1990. These known devices have certain disadvantages such as insufficient brightness and limited viewing angle. The present invention is aimed to provide a front light module that overcomes the above problems encountered in the prior art techniques.
FIG. 1A of the attached drawings shows a conventional front light module and FIG. 1B particularly shows a light guide plate of the conventional front light module. The conventional front light module, generally designated with reference numeral 900, comprises a light guide plate 901 having a step-like light emitting surface 902 and an opposite back surface 903 and end surfaces 904 (only one being visible in the drawings) connecting between the light emitting surface 902 and the backs surface 903. A light source 905 is arranged adjacent to each end surface 904 of the light guide plate 901 and light 920 emitted from the light source 905 travels into the light guide plate 901 via the end surface 904. Each step of the light emitting surface 902 has an inclined riser face 906 by which the light 920 from the light source 905 is reflected toward and through the back surface 903, as indicated by reference numeral 921, to reach a reflector 930 located adjacent to the back surface 903. As mentioned above, the conventional design has the drawback of a narrow viewing angle, which does not meet the requirement for general consumer products.